Influence of the Development History of Nozzle Wall Boundary Layer upon Wave Generation on a Liquid Jet Free Surface

スポンサーリンク

概要

• 論文の詳細を見る

• The relation between the development of the wall boundary layer in a convergent nozzle and free surface waves on the emanated liquid jet has been investigated experimentally. In the convergent nozzle, which forms a water jet along a flat back wall, the velocity profiles of the wall boundary layer were measured using a laser Doppler velocimeter with jet average velocities of <I>U</I><SUB>0</SUB> = 5, 10 and 15 m/s. The property of free-surface waves and the intermittency factor of free surface fluctuations were also determined by photography and an optical measurement technique, using laser beam refraction on the jet surface. For the lowest velocity case <I>U</I><SUB>0</SUB> = 5 m/s, the mean velocity profiles of the boundary layer under the pressure gradient in the convergent nozzle indicated an inverse transition from turbulent to laminar boundary layer, so-called relaminarization. On the other hand, for the higher velocity case <I>U</I><SUB>0</SUB> ≥ 10 m/s, the relaminarization in the convergent section became incomplete. For these cases, the turbulent intensity near the wall increased significantly and the nozzle-exit boundary layer was restored quickly to a turbulent profile for a short parallel section immediately upstream of the nozzle exit plane. The increase in the velocity fluctuation near the wall promotes wave generation downstream of the nozzle exit plane. Therefore, the intermittence of the wave packet almost disappeared and the jet free surface was covered with continuous capillary waves when the turbulent boundary layer was separated from the nozzle exit.

• 一般社団法人 日本機械学会の論文

著者

• Kumamaru Hiroshige

  University Of Hyogo

• Itoh Kazuhiro

  University Of Hyogo

関連論文

• Mixing of Horizontally Injected High-Density Solution in Vertically Upward Low-Velocity Water Flow
• Internal-Shear Mode Instabilities on High-Speed Liquid Jet, (II) : Experimental Analysis of Curved Target Flow
• Internal-Shear Mode Instabilities on High-Speed Liquid Jet, (I) : Characteristics of Linear Solutions
• Three-Dimensional Numerical Calculations on Liquid-Metal Magneto-hydrodynamic Flow through Circular Pipe in Magnetic-Field Inlet-Region
• Influence of the Development History of Nozzle Wall Boundary Layer upon Wave Generation on a Liquid Jet Free Surface

スポンサーリンク